Mechanical and electro-mechanical manipulator arms are commonly equipped with end effectors such as a pair of tongs or jaws that are capable of gripping and lifting loads in the range of 20-100 lbs. Some end effectors such as nut runners have specialized functions such as turning bolts, nuts and the like. Others include grips having fingers, for holding wrenches or grips for opening boxes, or removing lids, hammering, hooking, applying leverage and the like.
The arms are commonly used in remotely controlled, servo-driven manipulator systems, called servo-manipulators, such as those currently being developed at the Oak Ridge National Laboratory of the Department of Energy for advanced applications. These systems operate the arms of their master and slave units across distances of 500 feet or more.
Slave servo-manipulators have been developed that are particularly suited for remote handling of highly radioactive materials in hot-cell facilities. Because human access to the hot-cells is not permitted, it is the practice in these facilities to employ more than one slave unit in each hot-cell so that they can perform maintenance functions on each another. To this end, the servo-manipulators have been modularized so that each servo-manipulator can be broken-down by the other unit into modularized parts. The module needing servicing can be replaced with a module from a store of spare modules located in the hot cell.
The operations necessary for the breakdown and replacement of the modules requires a wide range of different and intricate mechanical operations. The manipulator effecting the servicing usually must change end effectors to execute all of the servicing steps.
Thus, there is a need for making the end effectors both replaceable and easily interchangeable.
Heretofore, end effectors had been attached to the rest of the servo-manipulators with bolts or the like. These prior arrangements are difficult for the servo-manipulator to connect and disconnect, particularly if the caustic environment of the hot-cell causes the bolts to corrode and stick. If any one bolt becomes so stuck that the servo-manipulator lacks the strength to loosen it, then that servo-manipulator is unserviceable and the regular operations of the hot-cell facility must be interrupted to correct the problem.
When one servo-manipulator is servicing another one located in the hot-cell, the other unit is oftentimes not available to assist the first one with its change of end effectors. Accordingly, there is a need for an arrangement which permits rapid change of end effectors on servo-manipulators by remote control, and preferably, by remotely operating a single servo-manipulator, such that it can change its own end effector, instead of having to require the assistance of a second servo-manipulator.